It has been discovered that the vibrissaeless rat blisters because of a suprabasilar adhesion defect, that the exfoliative mouse suffers a transient purulent conjunctivitis, exfoliates and may die. Survivors continue to have intermittant hair loss; masked rats have blepharitis accompanied by alopecia. Pasteurella organisms appear to be playing a role. The motheaten mouse has been found to have a hyperimmunoglobulinemia and usually dies of an autoimmune disease. Germfree environment has no effect on prolonging survival. An attempt has been made to classify and summarize genodermatoses involving neoplasia.